I kept needing simple dev tools — a JSON formatter here, a Base64 decoder there — and every site was bloated with ads, popups, and cookie banners. So I built my own.
DevTools.run is a collection of 20 free developer tools that run entirely in your browser. Nothing is sent to a server. No accounts, no tracking, no ads.
What's included
- JSON Formatter & Validator — paste messy JSON, get it formatted with syntax highlighting
- Base64 Encoder/Decoder — handles text and files
- Hash Generator — MD5, SHA-1, SHA-256 using Web Crypto API
- JWT Decoder — inspect header, payload, and expiration
- Regex Tester — real-time match highlighting
- Unix Timestamp Converter — seconds/milliseconds to human dates
- Color Converter — HEX, RGB, HSL with live preview
- Markdown Preview — write and render in real-time
- URL Encoder/Decoder — encodeURI vs encodeURIComponent
- Lorem Ipsum Generator — paragraphs, sentences, or words
- Text Diff — side-by-side comparison with line highlighting
- Password Generator — customizable with strength indicator
- Cron Expression Parser — human-readable descriptions + upcoming runs
- QR Code Generator — canvas-based, download as PNG
- UUID Generator — bulk generate v4 UUIDs
- Unix Permissions Calculator — toggle rwx, see numeric + symbolic
- SQL Formatter — keyword uppercasing and indentation
- YAML/JSON Converter — built-in parser, no external deps
- Aspect Ratio Calculator — detect or calculate from dimensions
- SOL/USD Calculator — live Solana prices from CoinGecko
Tech stack
- Next.js (App Router)
- TypeScript
- Tailwind CSS
- Zero external dependencies for the tools — everything uses native browser APIs (Web Crypto, Canvas, etc.)
- Deployed on Vercel
Why client-side matters
Every tool runs in your browser. Your data never leaves your machine. That means:
- You can paste API keys, tokens, and passwords into the JWT decoder or Base64 tool without worrying
- No server costs = stays free forever
- Works offline after first load
Open source
The whole thing is on GitHub: github.com/TateLyman/devtools-run
If there's a tool you want added, open an issue or PR. I'm actively adding more.
I also published a few CLI tools on npm if you prefer the terminal:
- jsonfix-cli — fix broken JSON (trailing commas, comments, single quotes)
- csvkit-cli — CSV swiss army knife
- portfind-cli — find/kill processes on ports
All zero dependencies, pure Node.js.
If any of these tools save you time, tips are appreciated:
SOL: NaTTUfDDQ8U1RBqb9q5rz6vJ22cWrrT5UAsXuxnb2Wr
Would love feedback. What tools do you use daily that you wish had a simpler version?
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